This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
3GPPthird generation partnership projectBWbandwidthCAcarrier aggregationCCcomponent carrierCSGclosed subscriber groupDCdual carrierDLdownlink (eNB towards UE)eNBE-UTRAN Node B (evolved Node B)EPCevolved packet coreE-UTRANevolved UTRAN (LTE)HSDPAhigh speed downlink packet accessHSUPAhigh speed uplink packet accessLTElong term evolution of UTRAN (E-UTRAN)LTE-ALTE advancedMACmedium access control (layer 2, L2)MM/MMEmobility management/mobility management entityNodeBbase stationOFDMAorthogonal frequency division multiple accessO&Moperations and maintenancePDCPpacket data convergence protocolPHYphysical (layer 1, L1)RelreleaseRLCradio link controlRRCradio resource controlRRMradio resource managementRSRPreference signal received powerRSRQreference signal received qualitySGWserving gatewaySC-FDMAsingle carrier, frequency division multiple accessUEuser equipment, such as a mobile station, mobilenode or mobile terminalULuplink (UE towards eNB)UTRANuniversal terrestrial radio access network
The specification of a communication system known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA) has been a working project within the 3GPP. As specified the DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest is 3GPP TS 36.300, V8.11.0 (2009 September), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (EUTRA) and Evolved Universal Terrestrial Access Network (EUTRAN); Overall description; Stage 2 (Release 8), incorporated by reference herein in its entirety. This system may be referred to for convenience as LTE Rel-8. In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.211, 36.311, 36.312, etc.) may be seen as describing the Release 8 LTE system. More recently, Release 9 versions of at least some of these specifications have been published including 3GPP TS 36.300, V9.1.0 (2009 September).
FIG. 1A reproduces FIG. 4.1 of 3GPP TS 36.300 V8.11.0, and shows the overall architecture of the EUTRAN system (Rel-8). The E-UTRAN system includes eNBs, providing the E-UTRAN user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE (not shown). The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME by means of a S1 MME interface and to an S-GW by means of a S1 interface (MME/S-GW). The S1 interface supports a many-to-many relationship between MMEs/S-GWs and eNBs.
The eNB hosts the following functions:                functions for RRM: RRC, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both UL and DL (scheduling);        IP header compression and encryption of the user data stream;        selection of a MME at UE attachment;        routing of User Plane data towards the EPC (MME/S-GW);        scheduling and transmission of paging messages (originated from the MME);        scheduling and transmission of broadcast information (originated from the MME or O&M); and        a measurement and measurement reporting configuration for mobility and scheduling.        
Of particular interest herein are the further releases of 3GPP LTE (e.g., LTE Rel-10) targeted towards future IMTA systems, referred to herein for convenience simply as LTE-Advanced (LTE-A). Reference in this regard may be made to 3GPP TR 36.913, V9.0.0 (2009 December), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for EUTRA (LTE-Advanced) (Release 9). A goal of LTE-A is to provide significantly enhanced services by means of higher data rates and lower latency with reduced cost. LTE-A is directed toward extending and optimizing the 3GPP LTE Rel-8 radio access technologies to provide higher data rates at lower cost. LTE-A will be a more optimized radio system fulfilling the ITU-R requirements for IMT-Advanced while keeping the backward compatibility with LTE Rel-8.
As is specified in 3GPP TR 36.913, LTE-A should operate in spectrum allocations of different sizes, including wider spectrum allocations than those of LTE Rel-8 (e.g., up to 100 MHz) to achieve the peak data rate of 100 Mbit/s for high mobility and 1 Gbit/s for low mobility. It has been agreed that carrier aggregation is to be considered for LTE-A in order to support bandwidths larger than 20 MHz. Carrier aggregation (CA), where two or more component carriers (CCs) are aggregated, is considered for LTE-A in order to support transmission bandwidths larger than 20 MHz. The carrier aggregation could be contiguous or non-contiguous. This technique, as a bandwidth extension, can provide significant gains in terms of peak data rate and cell throughput as compared to non-aggregated operation as in LTE Rel-8.
A terminal may simultaneously receive one or multiple component carriers depending on its capabilities. A LTE-A terminal with reception capability beyond 20 MHz can simultaneously receive transmissions on multiple component carriers. A LTE Rel-8 terminal can receive transmissions on a single component carrier only, provided that the structure of the component carrier follows the Rel-8 specifications. Moreover, it is required that LTE-A should be backwards compatible with Rel-8 LTE in the sense that a Rel-8 LTE terminal should be operable in the LTE-A system, and that a LTE-A terminal should be operable in a Rel-8 LTE system.
FIG. 1B shows one non-limiting example of carrier aggregation, where M Rel-8 component carriers are combined together to form an MHRel-8 BW (e.g. 5 H 20 MHz=100 MHz, given M=5). Rel-8 terminals receive/transmit on one component carrier, whereas LTE-A terminals may receive/transmit on multiple component carriers simultaneously to achieve higher (wider) bandwidths.
Based on a latest agreement from RAN2#68bis it was decided that the UE can be configured with deactivated CCs. For a deactivated DL CC the UE does not receive the PDCCH or PDSCH, and no CQI-like measurements. For an activated DL CC the UE receives PDSCH and PDCCH, if present. Activation/deactivation per CC or in common may be used. CCs are activated by L1 or MAC. In addition, CCs are deactivated by MAC or implicitly.
Additionally it was agreed that measurements on an activated CC can be done without gaps, and Rel-8/Rel-9 events are to be generalized.
It has not yet been discussed in detail how the handling of the measurements will be achieved. One obvious way forward is to reuse existing E-UTRAN mobility measurements and reporting. Reference in this regard can be made to 3GPP TS 36.331 V9.1.0 (2009 December) Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) Radio Resource Control (RRC); Protocol specification (Release 9), section 5.5.
It also has been acknowledged by RAN4 that if the UE supports carrier aggregation, which would allow it to simultaneously receive considered carriers, the UE hardware has the capability to perform mobility measurements without measurement gaps, even if the carrier is not active, (e.g., is only configured).
As is defined in 3GPP TS 36.331, section 5.5.1, “measurement gaps” are periods that the UE may use to perform measurements, i.e., no (UL, DL) transmissions are scheduled.
Further reference with regard to carrier aggregation can be made to 3GPP TSG-RAN WG2 #68bis, Tdoc-R2-100531, Valencia, Spain. 18-22 Jan. 2010, Source: NTT Docomo, Inc., Title: Carrier aggregation deployment scenarios.
E-UTRAN mobility measurements and functionality as described in the above-referenced 3GPP TS 36.331, and performance is described in 3GPP TS 36.133 V9.2.0 (2009 December) Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Requirements for support of radio resource management (Release 9).
UTRAN DC-HSDPA mobility is based on a primary carrier and for DC-HSUPA independent thresholds are assumed for each carrier.